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Finding the Fourth Proportional to 620.28, 855.72 and 399.15

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Solution

The fourth proportional to 620.28, 855.72 and 399.15 is: 550.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.28 : 855.72 = 399.15 : x
  2. Step 2: Convert to fraction form
    620.28/855.72 = 399.15/x
  3. Step 3: Cross multiply
    620.28x = 855.72 × 399.15
  4. Step 4: Simplify right side
    620.28x = 341,560.64
  5. Step 5: Solve for x
    x = 341,560.64/620.28
  6. Step 6: Final answer
    x = 550.66

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.